Messages in this thread Patch in this message | | | From | Olivier Moysan <> | Subject | [PATCH 5/5] iio: adc: stm32-dfsdm: add comment for 16 bits record | Date | Wed, 19 Jun 2019 15:03:51 +0200 |
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Add a comment on DMA configuration for 16 bits record.
Signed-off-by: Olivier Moysan <olivier.moysan@st.com> --- drivers/iio/adc/stm32-dfsdm-adc.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c index d855a605eab6..ee1e0569d0e1 100644 --- a/drivers/iio/adc/stm32-dfsdm-adc.c +++ b/drivers/iio/adc/stm32-dfsdm-adc.c @@ -918,6 +918,11 @@ static void stm32_dfsdm_dma_buffer_done(void *data) static int stm32_dfsdm_adc_dma_start(struct iio_dev *indio_dev) { struct stm32_dfsdm_adc *adc = iio_priv(indio_dev); + /* + * The DFSDM supports half-word transfers. However, for 16 bits record, + * 4 bytes buswidth is kept, to avoid losing samples LSBs when left + * shift is required. + */ struct dma_slave_config config = { .src_addr = (dma_addr_t)adc->dfsdm->phys_base, .src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES, -- 2.7.4
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